This essay begins with the proposal of the "pedagogy of the concept" according to Deleuze and Guattari. On this basis, I emphasize and explore the assertion that every Philosophy demands, as its internal condition, "relationary traces". Among the relationary traces defined by this pedagogy of the concept, I choose the "friend" as a feature who characterizes a given philosophical thought. I attempt, after that, to define, in a general way, the friend and the landscape of friendship in the Plato's, Nietzsche's, Heidegger's and Foucault's philosophies.

Deleuze and Guattari observe accurately that friend and friendship are almost absent concerns from the philosophical thought, with the rare exception for Maurice Blanchot's book on friendship (DELEUZE & GUATTARI, 1991, p. 10). When philosophers think over these questions, friend and friendship are usually taken into account from an ethical point of view. Deleuze and Guattari wonder why this issue has been so scarcely approached from the point of view of the concepts creation, since, etymologically, the philosopher is the friend of knowledge.

"Friend" is the character who testifies the Greek birth of Philosophy. The philosopher is the "friend" of the "knowledge". But, the friends of the Philosophy would be, therefore, as far as they share knowledge, friends one to another? Would they be attached to reciprocity because of the object of its friendship? And how could these friends impart their friendship?

The friendship as character of the Philosophy itself means that such relation appears from inside the thought. The friend comes from a relation that arises from the plan of the concepts. The plan where this friendship takes place - which I call the friendship of the concept from now on - is impersonal and, at the same time, highly colorful. According to Deleuze and Guattari, all concepts send out certain "afects" and "percepts" that cause determined sensations. Any concept might be felt as sympathetic or unpleasant (DELEUZE & GUATTARI, 1991, p. 124-125). For instance, Foucault rejected the Deleuzean concept of "desire", which he considered as being one of the traces in the historical mode of the Christian subjectivation (the "flesh") (FOUCAULT, 1984, p. 221 e ss; FOUCAULT, 1988, p. 198 e ss; FOUCAULT, 1989, p. 136-137). Deleuze, in return, had an aversion to the Foucaultian concept of "pleasure", which seemed to him to be limited to its object of satisfaction, and not to the true force of life (DELEUZE, 1994).

The afects and percepts emitted by the concepts are not sensations to be confounded with experienced individual feelings, in a historical field, by the psycho-social characters of the philosophers who created those concepts (DELEUZE & GUATTARI,1991,p. 68). In fact, the sensations produced by a concept do not coincide with the ones the philosopher might go through as an individual; or, if they do, they feel as much as if another individual had gone through them, that's because, state Deleuze and Guattari, "the philosophers' face and body shelter some characters who assign to them a strange mood, most of all in their eyes, as if another person saw through them" (Ibidem, p. 71).

The concepts give us these eyes that are another person's eyes inside of us. The regard of the concept is a sensation that does not come from the very eyes or from personal feelings. The concepts make us exchange nobody's regards.

But how come being a friend, specially a friend of knowledge, being nobody?

This question aims at investigating the territory of the friendship of the concept and, as I have indicated, if it is a highly assorted plan or dimension, I am allowed to hypothetically think that the friendship of the concept might be detected on certain historical periods or even on each thinker. So, I will try to define and illustrate, from elements borrowed from Deleuze and Guattary, to an extent that fits this paper, four sorts of friendship, the Greek, the Nietzschean, the Heideggerian and the Foucaultian. In each one of them, I shall emphasize the percepts and affects that make up friendship as landscape and the friend as conceptual character. Such an inquiry is part of the "pedagogy of the concept" (DELEUZE & GUATTARI,1991,p. 17).

Then, what could be the friendship of the concept in the Ancient Greece, since the Greeks invented themselves as the friends of knowledge?

Throughout Plato's writings, banned the eternal Sophists, the true friends of knowledge were those which began a dialog whose goal was possessing a concept. Therefore, for example, the philosophers portrayed by Plato were not friends who, under a common decision, would have gathered together in order to spend hours discussing the Idea or the essence. On the contrary, friendship is the condition for the thought to be carried out. But, it does not mean that friendship presupposes the thought, because it begins along with the thought. Properly speaking, I may say that friendship is an internal condition to thought, in the sense established by Deleuze and Guattari as an "intrinsic presence to thought" (DELEUZE & GUATTARI,1991,p. 9). As far as the friends of knowledge are in position to exchange ideas, that is, they set up some debate concerning the truth of any subject or concept, we are able to say that thinking and learning happens. There is no thought without the friend.

The conversation among the friends of Philosophy develops a certain dialectics, which Plato called amphibetesis. It also allowed comparing the differences among the most important occupations in the city, including Philosophy, in view of the definition of the legitimate government, which is a special "friend of knowledge" (PLATO, 1964, 259C-262a). Every philosopher presented himself as the friend of the object whose concept he intended to grasp, for instance, truth, love, or state. Then, with relation to the thing to be claimed, two philosophers disputed as pretenders that aspire to the requested concept. The friendship that shared the disputed thing was the only condition through which the truth or essence of this thing might be intended.

The Greek philosophical friendship was based on the idea that the world makes us wonder (thaumazein), that is, a kind of curiosity that both impels Humans to escape from the world of appearances and makes them question the Being of existing things, from a rational attitude. Though this wondering gesture did not lead everybody to the same truth, it guided Humans to claim the essence of some object. At this extent, as I have remarked, every man and every philosopher is a friend. And the knowledge may be taught on the basis of this friendship that contends.

From the Nineteenth Century on, especially with Nietzsche and Heidegger, the world's philosophical wondering has shifted its meaning. With Nietzsche, it has been painted with the colors of suspicion in relation to the philosophical creation and, consequently, the philosophical friendship was put under inquiry. With Heidegger, in a certain way, the philosophical wondering has been affected by a terrifying or astonishing attitude in face of a happening that went beyond and froze Reason's strengths. This overwhelming happening has thrown Humans in a sort of indetermination or vacuum, which blurred their faculty to question the essence of beings.

It follows that the principal problem in the contemporary Philosophy is how to go on thinking after this extreme event, which exhausted the forces of Reason. In a certain way, the friends could not afford enjoying their friendship confidently as they did in the past. They could not be friends as the Greek were, for, if it is true that the world makes us wonder, then, the wonder exceeded our consciousness, threatening the old and moderate friends' dialects.

In order to exemplify what I mean, we shall examine what friendship became through the waste land Philosophy after Nietzsche and Heidegger.

In the analyses of Plato's metaphysics, Nietzsche warned that we had inherited from the Greek friends a dangerous image to Philosophy. Nietzsche explained that the game among the friends of Philosophy was rotten in its very roots. Philosophy was addicted to the will to truth. It means that, behind the Greek Philosophy, there might have been a kind of moral training grounded on the idea that true ideas should have a steady essence and that, hence, its origin was not supposed to change. Thus, Nietzsche would have found that the dialects, which ran among the friends philosophers, was built upon a fake idol. The quarrel for truth would not be the leading path for the pretenders to grasp the essence of an object.

According to Nietzsche, the philosopher should practice the "art of suspecting" (NIETZSCHE, 1970, p. 215-216), being its most useful tool the hammer (NIETZSCHE, 1954, p. 676 (§ 211)). Thus, we are miles away from the Greek philosophical dialog, because the philosophers had learnt from Nietzsche that the ideas were not extracted from the Philosophy's haven, which they could touch through a sort of contemplation. Nietzsche argued that the concepts had a sublunary birth and that they were human creation and, consequently, they bore the empirical circumstances of the experiments. They were not ready, waiting for the most serious philosophers - those ones most devoted to contemplation, those few friends of knowledge - to collect them in their supersensible floating. The concepts had an origin, but a low origin oftentimes.

Some of those earthly concepts might be promoted to act like ideal world's entities through the artifact or fiction of transcendence. Then, they would be twice as much deceiving. First, because they hide their mortal birth. Second, because they pass over the cheat that transcendence may be creative, in a certain way, replacing and blessing the philosopher. Nietzsche's lesson is clear and sound: we must be suspicious about the concepts because of their authors.

After this crack, two opposite fields came up in Philosophy, each one of them having an appropriate friend of knowledge. In the first field, as said Nietzsche, are the "Philosophy's workmen" (NIETZSCHE, 1954, p. 676 (§ 211)) that are inspired by the "dignifying model of Kant and Hegel" (Ibidem). The Philosophy's workmen had been assigned the hard duty to evaluate the concept inherited from tradition in order to watch over the established values. In the opposite field, are the "true philosophers" (Ibidem), to which knowing means creating" (Ibidem). The latter use the products of the workmen as a hammer in order to destroy the old concepts, so that brand new values could be created. Accordingly, Nietzsche promptly rejected the nickname of friend of the knowledge to designate the philosopher. He stated:

So far, all the promoters of man have been called philosophers  they seldom had by themselves the feeling of being friends of knowledge, because they are, most of all, dangerous madmen and question marks  they found their work hard, not desirable, ungrateful and not to be put off, but they had recognized its greatness by representing the bad consciousness of the times they lived in (Ibidem, p. 677)

That's why, both in the relation of the philosopher with his age and in the relation between the workmen of Philosophy with the true philosophers arise a tension that usually merges familiarity and suspicion. On the one hand, if the workers succeed, the old concepts along with the values they bring are, in a way, made eternal. In this case, a harmful friendship among the philosophers comes up, for it is based on the slave's morals, as would say Nietzsche, trough which transcendent values keep the ancient ones and neglect the philosophical creation. On the other hand, if the Philosophy's workers are taken as hammers by the inventive philosophers, the friendship among them succeed.

What could then we say about the friendship of philosophers in the Nietzschean mode?

It must be performed at a distance, due to concentration each philosopher must keep to their own task, that is, the demolition of concepts and values of the past. The philosopher becomes a kind of Hercules  worker and creator -, whose works require some olympic intensity, which puts him apart from relationship. The olympic philosopher must be silent and the friendship among philosophers lives on tacit and virtual meetings, not accomplished but full of promises. Friends only get close to each other at a glance, in the minute pause to breathe to an instant nodding, through paths that cross by chance. Surprisingly, the friendship of the philosophers is caused by the distance, as said Nietzsche, "who knows how to be the loneliest will be the greatest" (NIETZSCHE, 1954, p. 678) and "the one that became lonely by a whim of the nature, due to a estranger mixture of desires, talents and aspirations, knows how inconceivably having a friend is" (Idem, [s.d.], p. 97). Nietzsche stated somewhere else, in verses:

I know the spirit of many a man/But I do not know who am I/My eyes are too close to me/I am nor what I see neither what I have seen./ It would be of great advantage to myself/If I could be far from myself./ Not so distant as my enemy, clearly!/ The closest friend is yet too far/But in-between us there is the halfway (NIETZSCHE, 2002, p. 28-29)

Consequently, the philosopher shall ban the philosophical conversation in the Platonic sense, for it seems to him a spoiling exercise, infected by a vicious dialects, in which there is no room for a creative friendship. As asserted Nietzsche, the philosophical conversation is "a sort of frightfully self-indulgent and childish dialects" (NIETZSCHE, 1954, p. 1028). A philosopher always demands, as friend of his pupils, some silence, in order to avoid the fallacious dialogs, as exemplifies the relation between Zarathoustra and his animals. The language itself, according to Nietzsche, has a reactive role, for words usually are in delay in regard to the body, which instantly grasps the happenings.

Where could we find the friend-philosopher in Heidegger's thought?

Heidegger described the great philosophical systems as powerful machines thata produced the forgetfulness of the Being and made Humans turn their eyes toward the beings' world, that is, of the existing things. That is why the Humans have fallen apart from Being, which keeps the truth of the being's essence. In a world living in the forgetfulness, the rescue of the Being is the most important and difficult theoretical and practical task. According to the famous bucolic and wild Heideggerian image, the Humans live in a forest clearing where the Being grants presence to them. So, we are supposed to be both obfuscated by the blind light in this clearing and partially protected from it by the housing that language provides to us. If the Being does not appear or if it turns around from the clearing where the forest's inhabitants get together, the forgetfulness might throw on Man its shadow. Language, due to its protection role in the clearing, endures the circumstances of the forgetfulness of Being, since, as the house where Man nestles, it protects from the blinding brightness of the Being and, at the same time, absorbs and translates its shining truth.

Then, how would it be possible to think in a world darkened by the forgetfulness of the Being? And what could be said about the friendship for the knowledge in a shaded world? Heidegger himself answered:

the forgetfulness of the Being was often represented as if it was, to express it in an image, the umbrella that the distraction of a philosophy professor forgot in some corner. However, the forgetfulness does not affect the essence of the Being as something apparently apart from it. It belongs to the task of the Being itself and reigns as destination to its essence (HEIDEGGER, 1969, p. 50-51).

In fact, the forgetfulness of the Being announces its being-there in two opposite ways. First, the Man lives its essential indetermination as existent being and faces the Being to question it. Second, when trying to determine himself as being gifted with a special essence among the exiting beings, he shall be swallowed by the Forgetfulness of the Being and his fading is announced as an ontological catastrophe.

As long as the question of the Being is not presented in the perspective of the forgetfulness, the Man remains in the shade of the Being that recedes and under which he is forgotten, since he by mistake questions the existent beings and not the Being. The Man, because of his indeterminate essence, has the duty to investigate the question (HEIDEGGER, 1978, p. 35). The relative privilege of Man grants him to act like the "Being's shepherd" as his inner vocation, for the human being is extrinsically united to the place from which the truth of the Being is expressed. Thus, he is supposed "to guard and to protect it" (HEIDEGGER, 1979, p. 149-156). He "acquires the essential poverty of the shepherd, whose dignity lies on the fact that he has been called by the Being to keep its truth" (HEIDEGGER, 1979, p. 163).

The Man is as existing being as any animal, mineral or machine, but he should not look for his essence among the beings. This attitude would only make him rejoices with his supremacy among the beings, but he would not accomplish the possibility that this superiority assigns to him, that is, inquiring the indetermination of his essence in face of the Being.

By privilege, the shepherd is thrown in the clearing of the Being, he is in the opening. The clearing involves the Being and Man as in a fold, placing them in different sides, but wrapping them up in the same ontological tissue. The Being appears in the clearing place constituting the essence of the truth that becomes unveiled in the neighborhood of the Man. Though, at the same time, as the Being in its side of the fold discloses for the Man, the latter dives into an essential non-truth. The Being, thus, is at the same time close and at an undefeatable distance with regard to the Man, since this non-truth is the truth of the Being that remains unexplored as pure possibility to Humans. With Heidegger, the Humans have been banished from the agonistic circle of the Being, we are in the opening of the Being, where Man is confronted to the inhuman as his inherent existential quality.

The friends of the Philosophy are not anymore protected by the circle of the speech where they met to dispute the truth. The friends are petrified or ecstatic before what seems to be an ontological ecstasy from which they could neither escape nor redeem. Language itself, the Man's house, became stained by this indeterminate event, so that Man might only think over the inhuman features that make him sink. The rational dialogue has been ceased, deformed or interrupted by some vacuoles of silence.

The Man, according to Heidegger, is called to the clearing by the Being itself and nestles in the house of language, in order to quietly listen to the speech of the Being. As the Being's shepherd, the philosopher lives in huge pastures, whether plain or mountain, almost in total isolation with relation to other shepherds. Curiously, the undefeatable distance of loneliness compels the philosophers' silent friendship. His pastoral friendship is also the condition for the hearing of the Being, so that the friend of knowledge might be humbler then the eloquent Humanist or Greek philosopher.

We must listen to the Being in order to redress human existence, because the classic philosopher is the one who exactly lost the hearing of the Being, he forgot the shepherd job that the Being assigned to him in the clearing. The isolation of the open places and the alert ears to the winds of the endless landscapes are features that define the friendship of the concept in Heidegger's Philosophy. The master and the pupil silently walk through these desert vastnesses. The master only lesson is the attitude of hearing.

What might have said Foucault about the philosopher's friendship?

Foucault would have declared, according to Deleuze, that "Heidegger always fascinated him, but he only could understand him through Nietzsche, with Nietzsche (not vice-versa)" (DELEUZE, 1986, p. 120-121). Or else, "Foucault", declared Deleuze, "is surely at the same level as Heidegger, but in a total diverse way, he is the one that more deeply changed the image of thought" (DELEUZE, 1990, p. 130-131).

The renewal Foucault made mainly involved the constitution of the clearing or the world's indeterminate horizon where the Being appears. Such clearing, as Foucault understood it, is not anymore the huge landscape where the shepherd opens his ears, or else, where the light in this opening to the Being becomes audible. The clearing does not invite to a lone relationship anymore, because it is a field of forces. The shepherd of the Being, the friend-shepherd, is not in a listening attitude in order to put into words the vision in the opening. According to Foucault, explained once again Deleuze, the Being's clearing is revolved by the unnatural way by which what one sees and what one says coexists, due to the historical modes of seeing and saying (DELEUZE, 1986, p. 66).

The most essential in the way Foucault passes through the Heideggerian friendship plan is that seeing and saying do not (nor could they) match. It runs trough them the historical width of the Episteme and the crossfire of the power relations, which are enunciates and the visibilities' constituents. The Foucaultian friend looks to the clearing of the Being through Nietzschean eyes, so as to turn the pleasant character of the shepherd who herds into a warrior who move forward on a battlefield. The friends are friends for fighting. As testified Veyne,

Foucault was a warrior, told to me Jean-Claude Passeron, a man from the second function; a warrior is a man who can abstain from truth, who does not know more than prejudices, his own and his adversary's, and who has strength enough to attack without justifying himself (VEYNE, 1985, p. 933)

Such a warlike vision of the friendship fits a combatant Philosophy, since said Veyne inspecting Foucuault's morals, "a Philosophy does not have more than one use: making the war; not the previous war, but the current war. Thus, it must start by proving genealogically that there is no other truth in history, but this combat" (VEYNE, 1985, p. 941).

This is the most important about the Foucaultian friendship of the concept. The shepherd of the Being leaves both the relative passivity of listening and the wonder or obfuscation that took him in the glow of the clearing. He awakes for a world of forces that is not displayed in the distance of a horizon; on the contrary, the indetermination of the world involves and crosses him from all sides.

Any friendship, even that among philosophers, is one "technique of self" and it was performed through several issues in Greek ordinary life, for instance, in the democratic rules, in the justice, in love relationships and in the domain of the thought and the education, as showed Foucault in his analysis of the Alcibiades (FOUCAULT, 1989, p. 150).

Foucault when taking into account the friendship between people mentions the "affective tissue" that erforms a real situation of war. He stated that the ways of life are constructed in fields of force where the strategy defines the rules of the game. Approximately, we can also say that the friendship tissue is always weaved, even in Philosophy for

somebody may ask what, during these absurd, grotesque wars, in these demoniac slaughters, might have made people endure, after all? No doubt, it was the affective tissue. I do not mean that they went on fighting because they were in love to each other. But the honor, the courage, the dignity, the sacrifice, to leave the trench with the pal, in front of the pal, implied a very intense affective web. This does not mean at all: "Ah, here you have the homosexuality". I loath this sort of reasoning. No doubt we have there one of the conditions, not the only one, which allowed to bear that hell's life where people, during weeks, lurched in the mud, between corpses, the excrement, starving; and were drunk in the morning of the attack (FOUCAULT, 1981, p. 38-39).

Let us come back to my beginning question, that is, why do all philosophies include a friendship relation, in such way that we could make a visit to the concept of friend and to some landscapes of friendship according to some philosophers?

Deleuze and Guattari help us to give a general reply to this question, despite the diversity of the relation of friendship according to the chosen philosopher. The friend is precisely a "feature of the conceptual character" who has to do with the "psychosocial characters" (DELEUZE & GUATTARI, 1991, p. 68). The friend presents himself together with any concept. When a philosopher creates a concept or when somebody studies a philosophical thought, automatically, this character comes alive. Though the existential feature of the concept is related with experienced situations, it owes to the pathos of the concept its expression, given that

the conceptual features hold a relationship to its time and to the historical scene, which only the psychosocial characters might evaluate. But, in reverse, the physical and mental movements of the psychosocial types, their pathological symptoms, their relationary attitudes, their existential ways, their legal status, become subject to the pure determination of thought, which pull them out either from the historical states in a given a society or from the individuals' experiences, and make them turn into features of conceptual characters (DELEUZE & GUATTARI, 1991, p. 68).

The authors' lesson concerning this question is that we can speak, properly, of a Platonic friendship, since it involves the relation with the Idea and with the truth; of a Nietzschean friendship based on the diffidence; of a Heideggerian friendship based on the hearing in the Being's clearing; and of a Foucaultian friendship in a battlefield. Even though we can describe all these kinds of friendship along with their personal qualities, which contain certain existential traces, in fact, they arise from the plan of the concepts. Every philosophical thought builds some friendship relation as a "relationary trace" (DELEUZE & GUATTARI, 1991, p. 69) inherent to a "pedagogy of the concept" (Ibidem, p. 17).

Deleuze himself outlined the features of the friendship we could afford in our days, mainly taking into its role to the philosophical thought. Through the letters exchanged between him and the writer Dionys Mascolo, in 1988, a beautiful reflection on friendship was accomplished (DELEUZE, 2003, p. 304-310. Both of them agreed that the friendship remains the condition to think and to learn, but the friends are not as the Greek philosophers who gathered together in order to talk around one determined object whose concept was to be conquered. To be a friend, in our days, thought them, does not mean to set out a dialogue, since the friendship as a way of living entered into a sort of mined field where the friend's movements had become suspicious. All conversation that could have started among friends is undermined from its beginning by an insane discursive production, which penetrates and dries out the creative vein of the friendship. So, being a friend and thinking must go on through an apparently contradictory way, because, cherishing a friendship is to follow with the friend by shady and silent zones. Therefore, it is neither necessary nor wise "speaking with the friend, sharing souvenirs with him, but, on the contrary, is with him that we go through tests like the amnesia, the aphasia, necessary to all thought" (Ibidem, p. 307).